The principal study within this project concerns the transient kinetics of the sodium pump. A collaboration with J. Froehlich of NIA and K. Fendler of Max Planck (Frankfurt) has related the E1P/E2P conformational transition to the electrogenic sodium current. Work in progress is directed to determining the extent to which oligomeric interactions of the sodium pump contribute to the efficiency of cation transport. In addition, R. Wayne Albers is collaborating with P. Sharma and N. Amin of the LNC in studies of the mechanism of the cdk5 kinase reaction and the kinetics of the interaction of this kinase with its activator.